Strokes are the third leading cause of death in the United States, causing approximately 177,000 deaths per year, and strokes are the number one cause of long-term disability in the United States, currently affecting nearly 5 million people. Strokes are caused by an abrupt interruption of the blood supply to the brain or spinal cord, thereby depriving the tissue of oxygen and resulting in tissue damage.
Strokes typically occur in one of two forms: (i) hemorrhagic stokes, which occur with the rupture of a blood vessel; and (ii) ischemic strokes, which occur with the obstruction of a blood vessel.
Rapid diagnosis is a key component of stroke treatment. This is because the treatment for an ischemic stroke may be contra-indicated for the treatment for a hemorrhagic stroke and, furthermore, the effectiveness of a particular treatment may be time-sensitive. More particularly, the current preferred treatment for an acute ischemic stroke, i.e., the administration of tPA to eliminate clots, is contra-indicated for a hemorrhagic stroke. Furthermore, the clinical data suggests that the medication used to treat ischemic strokes (i.e., tPA) is most effective if it is administered within 3 hours of the onset of the stroke. However, current diagnosis times, i.e., the time needed to identify that the patient is suffering from a stroke and to identify the hemorrhagic or ischemic nature of the stroke, frequently exceeds this 3 hour window. As a result, only a fraction of current ischemic stroke victims are timely treated with tPA.
Imaging is generally necessary to properly diagnose (and hence properly treat) a stroke. More particularly, imaging is generally necessary to: (i) distinguish strokes from other medical conditions; (ii) distinguish between the different types of strokes (i.e., hemorrhagic or ischemic); and (iii) determine appropriate treatments (e.g., the administration of tPA in the case of an ischemic stroke). Computerized Tomography (CT) has emerged as the key imaging modality in the diagnosis of strokes. CT scanners generally operate by directing X-rays into the body from a variety of positions, detecting the X-rays passing through the body, and then processing the detected X-rays so as to build a computer model of the patient's anatomy. This computer model can then be visualized so as to provide images of the patient's anatomy. It has been found that such CT scanning, including non-enhanced CT scanning, CT angiography scanning and CT perfusion scanning, is able to provide substantially all of the information needed to effectively diagnose (and hence properly treat) a stroke.
Unfortunately, in practice, the CT machine is typically located in the hospital's radiology department and the patient is typically received in the hospital's emergency room, and the “round-trip” time between the emergency room and the radiology department can frequently involve substantial delays, even in the best of hospitals. As a result, the time spent in transporting the patient from the emergency room to the radiology department and then back again can consume critical time which can compromise proper treatment of the patient.
Thus, there is an urgent need for a new and improved CT machine which is particularly well suited for use in stroke applications. More particularly, there is an urgent need for a small, mobile CT machine which can be pre-positioned in the emergency room and moved to the patient so that the patient can be scanned at their current location, thus effectively eliminating “round-trip” delays and dramatically reducing the time needed to properly diagnose the patient. It is also important that the CT machine be relatively inexpensive, so as to facilitate its rapid proliferation and widespread use, e.g., pre-positioning in substantially all hospital emergency rooms and wide availability in outlying, low-volume settings (e.g., rural hospitals, ships, etc.).
In this respect it should also be appreciated that CT scanners utilize X-ray tubes to generate the X-rays that are used to scan the patient. These X-ray tubes typically produce a substantial amount of heat when generating their X-rays, and this heat must generally be dissipated in order to improve image quality and increase component life. However, it can be troublesome to dissipate this heat, particularly inasmuch as the X-ray tube: (i) is encapsulated by the scanner housing, which tends to trap the heat from the X-ray tube; (ii) is generally in close proximity to many other internal scanner components, which can also trap heat; and (iii) must keep at least the emitter portion of the X-ray tube exposed, in order to permit the X-rays to exit the tube and pass into the patient. Such considerations have generally resulted in relatively complex X-ray tube assemblies comprising the X-ray tube and its associated cooling system, which can add to scanner size, weight and cost. This is particularly true inasmuch as the X-ray tubes (and hence their associated cooling systems) are generally mounted on large rotating drums which move the X-ray tubes concentrically about the patient so as to achieve the necessary scanning angles; such rotational mounting generally complicates the delivery of power and/or fluids to the X-ray tube's cooling system.
Thus, there is a need for a new and improved approach for cooling the X-ray tube in a CT scanner, so as to help reduce the overall size, weight and cost of the CT scanner.